Braided cover for spark-plug cables



H. RABEZZANA' Patented Jan. 1,*1929.

UNITI-:osrAT-EsPATENT OFFICE.

HECTOR RABEZZANA, F FLINT, HICHIGAN, ASSIGNOR T0 A C SPARK ILUG- COMPANY, OF FIINT, MICHIH'AN, A COMPANY OF MICHIGAN.

- BBAIDED COVER FOB SPARK-PLUG CABLES.

Application led `0ctoberv30, 1925. Serial INo. 65,791.

This invention relates to the provision of means to prevent heating of spark plu and preignition of the explosive mixture in gas engines.

It is closing of an electric circuit throughone of the sparkplugleads by the action of the distributor an induced current is produced in one or more of the adjacent cables. This l may,.especial1y in case of high speed engines,

be of sufficient magnitude to cause a small spark' ata second spark plug, which spark is of course not properly timed with reference to the cylinder operation of the cylinder with which this second spark is associated. This second spark may be of suilicient magnitude yto cause preignition, but even if not, it has been found troublesome in that it serves` toheat the spark plug.` A continuationbf this secondary sparking results in undesirably raising t e temperature of spark plugs as a whole.

It is an object of this invention to prevent this secondary sparkin to prevent preignition and to keep down t e excessive temperature of the spark plugs by preventing the induced currents in the electric cables adjacent to the cable actin to lire its charge. This object` is accomp ished by enclosing each. so cable with a metal sheath, and grounding this met-al sheath on the engine block. i

In the drawing accompanyin this specication is shown a practical em odiment o1 the idea. In Figure 1 is shown in side ele# vation an explosive' engine -equipped with my invention.

Figure 2 shows diagrammatically the Wiring and groundingarrangement for the cable sheath. Figure 3 shows in side elevation a 40 modified form of engine having my invention employed therewith. Fi re 4 is a side view of one of the electric ca les equipped with my metallic sheath. vReferring' to the drawin numeral 1 represents an explosive engine iavin at one end thereof the clutch housing 2. -t theopposite end ofthe engine is shown the generator ewiththclesflisdmouted above tlllie sanp. s ntra y ont ee 'neiss ownt e carburetor 5, the intake mldgnifold 6 and the exhaust manifold 7. Above the engine block is seen the distributor 8 and the water tubing 9. Connecting the coil 4 and the'distributor found thatsimultaneously with the.

8 is the usual electric cable 10, and from the distributor 8 are the several leads 11 extending one to each of the spark plugs 12.

In making these usual electric connections the several leads from the distributor to the spark plugs must necessarily be located quite closely to each other, especially in nthe vicinity of the distributor. Owin to the close relationship of these leads, w en the current is passing in one of them to cause the explosion 'of theA mixture in any one cylinder, induced currents occur in one or more of the other cables.- As explained above these induced currents may cause preigniticn and lare known to cause objectionable heatin of the spark plu To prevent these resL ts each of the ca les 11 is covered with a metal sheath as shown at 13 in Fi metal sheath may be of various constructions but it is preferred to make it of woven strands of wire. These cove s aregrounded to theengine block by individual wires con- .nectedA thereto and to the engine block as shown at 17 Vin Figure 1.

In Figure 2 the grounded connection is illustrated diagrammatically. The several leads from the distributor being shown, each with its ounded connectionwith a circle drawn to illustrate the ground.

Figure 3 shows another form ofgas engine.

. Here the only essential diierence consists in the location of the wiring. In this ligure the distributor is shown closely adjacent the generator 3 and the leads 11 from the distributor extends up side b side and into a metallic cylindrical mem er 14 -which is groundedto the engine block by its metallic support 15. The member 14 has the necessary outlets for the leads extendin to the spark plugs .as will be readily un erstood. In this type of motor instead of employing a separate wire from each lead and connecting said wire to the'motor block, the metallic sheath of the lead is unded b j engagement with member 14 an its metallic support 15.

By the provision of the arrangements described above the objectionable induction currents are `revented Attention 1s also called to the fact that ifV the future development of radio extends to the use of shorter wavelengths the pointma -soon be reached where the radiowave lengt gure 4. This which event the automobile spark plug would ralit of leads from said distributor to said causel considerable interference. This is spar plugs, each lead being an insulated another advantage resulting from the use of wire and having a metal sheath surrounding 10 Athis metallic sheath. its insulation and a ground for each metal 5 I claim: Sheath.

In combination with an explosive engine, a. In testimony whereof I aix my signature. plurality of spark plugs, a distributor, a plu- HECTOR RABEZZANA. 

